At present biofloc systems are becoming popular for their low-cost means of cleaning the culture water of fish and shrimp farms as well as providing an additional source of feed. To implement biofloc systems requires less investment as most of the factors are natural, proper sunlight, a source carbohydrate, and plenty of aeration are needed.
The system of this manages to convert uneaten feeds, feces even excess nutrients into the food. While ammonia and nitrates break down, both primary-producing autotrophic and heterotrophic bacteria to attract an ever-growing host of organisms like diatoms, fungi, protozoans, and various types of plankton.
Biofloc systems overcome difficulties with high animal-stocking densities and low filtration capacities like reduced water quality and high risk of disease outbreaks by recycling of proteins in the pond or tank. Only about 25% of the protein content of feeds is actually utilized by farmed species in the case of traditional fish farming systems.
Biofloc systems convert ammonium into microbial proteins which can be taken as food by filter feeders and thus these can double figure and save a big amount of money. As biofloc systems can give us a natural way to produce more seafood sustainably, while concurrently improving farm profitability.
There are some easy steps towards biofloc production of shrimp or tilapia these are bellowed.
Step 1: Tank or Pond Set-Up
Though it’s not difficult to convert traditional fish ponds into a biofloc system, it’s a challenging task too, as microbes, minerals, and heavy metals naturally based in the soil easily influence the parameters of the pond water and can affect the natural processes under the biofloc system.
Creating a biofloc system based solely on bacteria indoor tanks can be used, but without the presence of natural sunlight, algae won’t grow enough or won’t grow at all. These are so-called “brown biofloc systems” and brown in color.
If you use large ponds you need to install bottom drains to remove excess sludge occasionally. This is especially important when adding carbohydrates regularly.
Step 2: Aeration
As biofloc systems require a constant motion to continue both high levels of oxygen and to keep solids from settling as well, so after selecting the right pond or tank set-up, it’s time to think about the aeration system and do it properly.
Areas with movement will rapidly gain oxygen otherwise it will turn into the anaerobic zone which releases a huge amount of ammonia and methane too. So not to allow this, every pond, tank even raceway system must have a well-planned layout of aerators.
A typical Pond uses paddlewheel aerators usually. It is required about 6mg of oxygen per liter per hour in case of biofloc systems and it is recommended to start with at least 30 horsepower of aerators per hectare. The installation of paddlewheel aerators should be strategically so that a current is created in the pond.
Step 3: Pre-Seeding Beneficial Microbes
To accelerate the development of your biofloc system and stabilize your pond faster you need to pre-seed the culture water properly. You can do this by adding several commercial or homemade recipes to the culture water. A simple homemade recipe to quickly produce probiotic and prebiotic microbes uses wheat pollard on your farm.
Though most species would be benefited from the better water quality of biofloc systems, you must select species that best benefit from the extra proteins generated, by feeding and digesting the bioflocs themselves and these species are totally or partially filter feeders also.
High stocking densities may be considered and it is common to stock shrimp at densities of 150 to 250 post-larvae per square meter through a safe stocking density for tilapia would be up to 300 fries per cubic meter.
Many farmers try to use higher stocking densities but this significantly increases the risk of disease, compromising both the health and welfare of the animals.
Step 4: Balancing Carbon Source Input
Preventing the ammonia peaks at the start of the farming, you have to jump-start the growth and continue the development of biofloc in your pond or raceway system by making ensure the sufficient availability of carbohydrates.
The carbon in these types of carbohydrates enables heterotrophic bacteria not only to multiply but also to synthesize ammonia and thus maintaining water quality. You need to select only carbon sources and feed mixtures with a carbon-to-nitrogen ratio 10+ as this favors the growth of these heterotrophic bacteria.
Finally, to prevent ammonia peaks at later of the production system, this step should be repeated as well, especially when using high stocking densities in combination with large amounts of artificial feeds and this one is one of the difficult steps for successful biofloc systems.
Step 5: Biofloc Growth
Along with plenty of aeration, natural light, and available source of carbon, your biofloc numbers should be started to multiply quickly. The number of flocs will increase to about four to five units from about to zero per milliliter within a few weeks which depends on a variety of factors like water temperature, available nutrients, sunlight, and obviously the number of seeded bioflocs at the start of the operation.
An incredible density of up to 10 billion bacteria per cubic centimeter can be expected also. Monitoring properly the growth of these flocs can be done by using a beaker to collect several water samples at a depth of up to 20 centimeters, preferably in the late morning.
Step 6: Monitoring
Water samples must be regularly to be monitored to the pond water and determine the activity of the biofloc types plus their respective densities in the pond. In typical outdoor bioflocs consist of green along with algae and brown bacteria. The algae utilize sunlight for their growth mainly, while the bacteria consume leftover feeds. As algae primarily tend to multiply faster, that means a pond looks green at first, turning brown over the following weeks as bacterial colonies start to dominate as well. A tipping point will be reached wherein the water will remain brown with the stock growing and feeding volumes increasing.
Step 7: Water Parameters and Farm Infrastructure
When the biofloc system has turned brown then aeration must be increased to sustain the high rate of respiration and these rates at this stage can reach 6+mg per liter per hour hectare compared with the start of operations.
Any power failure right this time can quickly result in total crop failure due to a lack of oxygen and because in a low-oxygen environment many heterotrophic bacteria actually start producing ammonia as we all know. The aeration system needs to stay function normally for all times. So good maintenance and monitoring of the aerators themselves and the power system that provides the energy to run this system properly.
As the power grid in many Asian countries is not too reliable so you have to take necessary steps to continue uninterrupted electricity supply. Monitoring of water quality, especially dissolved oxygen and ammonia levels timely will give you a better idea of whether the system is working well or not.
Step 8: Monitoring and Control Of Farm Stock
Maintaining water quality along with a lower cost and without water exchange, another goal of a biofloc system is to improve growth rates and feeding efficiencies too, thereby betterment the profitability and sustainability of farming operations. To find out that how the farm is doing, daily monitoring of the performance of the farm stock, calculating, recording growth rates, and analyze it properly like a business, overall appearance, and stock survival is required to in count.
An average additional up to 0.5 units of growth can come from the biofloc in your system form a single unit of growth in your stock from the feed as it is estimated. So you need to notice a big jump when comparing current farm records with your previous records, not like a traditional non-biofloc farm operation.
Step 9: Harvest and Clean-Up
In the case of shrimp, it will be about up to 25 tons per hectare. If all steps have been followed properly, you can expect increased growth rates and survival, thus reducing overhead costs and improving profitability. But you must not be forgotten and underestimated proper cleaning and preparation of the pond set-up or raceway is vital after harvest time as well.
Although it might be seemed appealing to reuse the culture water as it is looked intensive effort to build up the populations of microorganisms, this is not advisable to you. Pathogens might have built up the culture and can pose a serious biosecurity risk too.
Metals can build up in the culture water, which may accumulate in your stock which makes it unsuitable for human consumption. So you are highly recommended cleaning up well before starting your next profitable batch.
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